The present invention is directed to a rail fastening system for fastening a rail to a rail support. The present invention particularly is directed to such a system for use in fastening a railroad rail to a rail support such as a concrete rail support, for example a concrete tie. The present invention also is directed to an assembly of such rail fastening system connected to a rail support.
It has become conventional in the industry to employ rail fasteners including ductile cast iron shoulder or support members fastened to rail supports, for example by being embedded in concrete ties. Such cast iron shoulders have proven ability to resist lateral forces transmitted by the foot of a rail as well as vertical forces exerted by various types of spring fastening clips.
One such system is disclosed in U.S. Pat. Nos. 5,520,330 and 5,566,882. Such known system employs fastening clips made of round steel that is bent to a shape such that it operates at the same time both in torsion and in flexion. Such combined stresses however are not recommended by some railroad engineers. Furthermore, the elastic range of the fastening and the actual toe load on the rail is limited. This system is employed primarily due to ease of installation and of tensioning of the spring clips.
Another known system is disclosed in U.S. Pat. No. 4,066,212. This system employs a threaded bolt that is embedded in a concrete tie. A flat plate-shaped spring steel clip is tensioned by a nut threaded onto the bolt such that one end of the spring steel clip is pressed downwardly against an elevated shoulder of the concrete tie and an opposite end of the steel spring clip is pressed downwardly against an insulating member interposed between a flange of a rail and the spring steel clip. The spring steel clip or spring blade has a relatively large hole in the center thereof for passage of the bolt. Such large hole can weaken the spring blade. Further, since tensioning is achieved by threading of the nut, or more recently by screws and inserts anchored in the concrete tie, the stressing of the spring blade is dependent on tightening torque and requires skilled workers and well adjusted power wrenches. Further, corrosion of the bolt threads creates maintenance difficulties. Nevertheless, such system, when employed properly, is desirable because of the use of the flat spring steel blade and the tensioning achieved thereby.